High prevalence of heart rhythm disturbance among HIV-positive people on methadone maintenance therapy

Higher dose of methadone an important risk factor

Michael Carter

Published: 13 August 2013

Spanish
investigators have identified a high prevalence of a potentially
life-threatening disturbance in heart rhythm among HIV-positive people
receiving methadone maintenance therapy. ECG examinations showed that 36% of
their participants had QTc prolongation, a condition that can lead to sudden
cardiac-related death.

Risk factors included liver cirrhosis caused by hepatitis C
virus (HCV), not taking antiretroviral therapy and higher doses of methadone.
The study is published in the online edition of Clinical Infectious Diseases. The investigators suggest that
HIV-positive people taking methadone should have ECG examinations.

A majority of patients in the study were also taking other medications that might affect the QT interval but this risk factor was less significant, the study authors estimate.

Jay W. Mason of the University of Utah School of Medicine, author of an
accompanying editorial, believes the study has wide clinical significance,
especially as it adds to what is already known about the risks associated with
methadone maintenance therapy: “Because there are safer, effective alternatives
to methadone for both maintenance programs and pain relief, should methadone be
withdrawn from the market?”, he asks.

Cardiovascular
disease is now an importance cause of serious illness and death in people with HIV. There is a higher prevalence of prolongation of the QTc interval – an
important marker of the regularity of heart rhythm – among people with HIV compared to
HIV-negative individuals. Prolongation of QTc can lead to a condition called
Torsades de Pointes, and to death because of serious irregularities in heartbeat.

Methadone
maintenance therapy is recommended as a safe and effective treatment for opioid
dependence. It certainly has benefits and is associated with the retention of
opioid-using HIV-positive people in care. However, cases of prolongation of
the QTc interval and Torsades de Pointes have been observed in people taking
higher methadone doses.

A team of
investigators in Barcelona wanted to find out more about the prevalence and
risk factors of prolongation of QTc interval among their cohort of 91
HIV-positive patients receiving methadone maintenance treatment for opioid
dependence. None of these people had underlying heart abnormalities or were
current drug users.

QTc interval was
assessed using ECG examinations 24 hours after the administration of methadone
maintenance therapy. A threshold of above 450 milliseconds (ms) was used to define QTc
interval prolongation and QTc above 500 ms was considered to represent a
significant risk of arrhythmia. The median methadone dose was 70 mg daily, but
31% of participants were on a daily dose higher than 100 mg.

Three-quarters of
the participants were taking HIV therapy and almost all of these individuals had an
undetectable viral load. HCV co-infection was present in 84 participants and 13%
had HCV-related liver cirrhosis.

Medications – such as antidepressants, antipsychotics and
antiepileptics – that involve a potential risk of prolongation of QTc interval
were widely used and taken by 58% of participants.

ECG examination
showed that 36% of participants had prolonged QTc interval and that 3% of
individuals had a QTc above 500 ms.

Several risk
factors were associated with longer QTc interval. These included not taking
antiretroviral therapy (p = 0.036). “Patients on antiretroviral therapy had a
shorter QTc interval compared with antiretroviral-naïve patients,” write the
authors. They suggest this “may reflect an improvement in disturbance of the
autonomic nervous system after antiretroviral therapy is initiated”.

Liver cirrhosis
caused by HCV co-infection was also a significant risk factor (p = 0.008). The
investigators believe this finding “is important since the prevalence of…HCV
among intravenous drug users with HIV infection is close to 90% and hepatitis C
liver disease is an increasingly recognised cause of morbidity and mortality in
these patients.”

Use of medications
with an effect on QTc interval was of borderline significance (p = 0.052). The
authors believe this underlines the importance of reviewing the medications
taken by people on methadone-maintenance therapy and checking for potential
drug-drug interactions.

There was also a
significant association between prolongation of QTc interval and higher doses
of methadone (p = 0.005). “This finding has significant clinical implications,”
suggest the authors, “since higher methadone doses are more effective than
lower doses in retaining patients and in reducing heroin and cocaine use during
treatment.”

They conclude,
“Clinicians should be aware of the risk of prolonged QTc interval and the need
for ECG monitoring in this specific HIV patient group so that cardiovascular
morbidity and mortality can be minimized.”

The author of the
editorial praises the investigators for adding to the understanding of QTc
interval in HIV-positive people on methadone-maintenance therapy. Although he
suggests that the researchers could have used a more stringent definition of
prolonged QTc interval, he nevertheless believes that the their finding of an
association with methadone dose is of great clinical significance, writing:
“While knowledge of the problem and careful patient management will save some
lives, these are weak answers in comparison with the obvious solution: stop
prescribing methadone.”

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

close

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends
checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member
of your healthcare team for advice tailored to your situation.